Sensitivity of neurons in the auditory midbrain of the grassfrog to temporal characteristics of sound. III. Stimulation with natural and synthetic mating calls.

Using an ensemble of natural and synthetic mating calls we studied the single unit (N = 189) and small neuronal group (91 unit pairs) responsiveness in the auditory midbrain of the grassfrog. We compared this responsiveness to that obtained for toneburst and sine-modulated stimuli in order to reveal the presence of so-called mating call detectors. Under the set of stimuli used 5% of the single units appeared to respond selectively to the natural mating call. Simultaneously recorded units appeared to have in about half of the cases identical properties, in the other half even completely complementary properties were found. These properties are related to the organizational structure of the torus semicircularis. A mechanism of feature extraction based on near coincident firings in simultaneously recorded neurons is presented.